115 research outputs found
Fractionation and characterization of two β-lactamases in Citrobacter diversus ULA-27 strain by chromatofocusing
No full textCitrobacter diversus ULA27 produces two forms of a chromosomal β-lactamase
No full textA multi-resistant clinical isolate of Citrobacter diversus, particularly resistant to penicillins and cephalosporins, has been studied. The strain produced constitutively high levels of β-lactamase which efficiently hydrolysed cephaloridine but not ampicillin. The apparent Km value for cephaloridine (125±25μM) was within the range usually observed for β-lactamases in similar bacteria. The strain possessed two forms of the enzyme as indicated by isoelectric focusing patterns, HPLC analysis and two pH optima. SDS-PAGE analysis indicated a single protein responsible for both forms. The strain possessed a single plasmid, as revealed by agarose gel electrophoresis, but β-lactamase production was not plasmid encoded. The available data indicate the β-lactamase(s) of C.diversus ULA27 to be chromosomally encoded. © 1987 The British Society for Antimicrobial Chemotherapy
Optimizing stable isotope sampling design in terrestrial movement ecology research
No full textThe recognition of adequate sampling designs is an interdisciplinary topic that has gained popularity over the last decades. In ecology, many research questions involve sampling across extensive and complex environmental gradients. This is the case for stable isotope analyses, which are widely used to characterize large-scale movement patterns and dietary preferences of organisms across taxa. Because natural-abundance stable isotope variation in the environment is incorporated into inert animal tissues, such as feathers or hair, it is possible to draw inferences about the type of food and water resources that individuals consumed and the locations where tissues were synthesized. However, modern stable isotope research can benefit from the implementation of robust statistical analyses and well-designed sampling approaches to improve geographic assignment interpretation. We employed hydrogen stable isotope simulations to study inferences regarding the probability of origin of migratory individuals and reveal gaps in sampling efforts while highlighting uncertainties of assignment model extrapolations. We present an integrative approach that explores multiple sampling strategies across species with different geographic ranges to understand advantages and limitations of animal movement inferences based on stable isotope data. We show the characteristics of different sampling strategies through geographic and isotopic gradients and establish a set of diagnostic tools that uncover the attributes of these gradients and evaluate uncertainties of model results. Our analysis demonstrates that sampling regimes should be evaluated in relation to specific research questions and study constraints, and that adopting a single method across species ranges can lead to a costly but less effective sampling strategy
On the formation of a dicloxacillin-p-hydroxymercuribenzoate suicide complex mediated by β-lactamase I from Bacillus cereus
No full textInvestigações sobre a materia corante do sangue
No full textO artigo traz novos caracteres sobre a substancia corante, contina nos corpulos sanguineos, sob o nome de arterina, refere os diferentes canais sanguíneos, e topicaliza com um resumo estas averiguações, com 2 observações sobre o comportamento de substancia
Diseño de un sistema de precisión para la medida de la deformación superficial de laminados metálicos en producción contina
No full textConsulta en la Biblioteca ETSI Industriales (7875)[ES] El objeto del presente Proyecto Fin de Carrera es el ¿Diseño de un
sistema de precisión para la medida de la deformación superficial de
laminados metálicos en producción continua¿, que nos permitirá realizar la
medición con precisión y en modo continuo, de la separación existente entre un
sensor y la superficie del laminado metálico que a su vez está siendo producido
también en forma continua. Esta información es debidamente procesada y
digitalizada para enviarla a un ordenador distante ubicado en la sala de control,
en donde se tomaran las decisiones oportunas.
Para la realización del PFC se ha dividido el diseño en dos etapas: la
primera dirigida al estudio y diseño constructivo del sensor que mide la
magnitud física. La segunda analizará y diseñará la red física encargada de
realizar la conexión y transporte de la información digital entre los sensores y el
ordenador.
Durante las dos etapas se han tenido en cuenta las restricciones y
exigencias en los dos diseños debido al ambiente industrial: temperaturas
cercanas a los 600ºC, ruido electromagnético del entorno, sensibilidad de la
medida, fácil mantenimiento, seguridad.Sánchez Llopis, C. (2008). Diseño de un sistema de precisión para la medida de la deformación superficial de laminados metálicos en producción contina. https://riunet.upv.es/handle/10251/34445.Archivo delegad
Calibration chain transformation improves the comparability of organic hydrogen and oxygen stable isotope data
No full textStable hydrogen and oxygen isotopic compositions (δ2H and δ18O, respectively) of animal tissues have been used to infer geographical origin or mobility based on the premise that the isotopic composition of tissue is systematically related to that of local water sources. Isotopic data for known-origin samples are required to quantify these tissue–environment relationships. Although many of such data have been published and could be reused by researchers, differences in the standards used for calibration and analytical procedures for different datasets limit the comparability of these data. We develop an algorithm that uses results from comparative analysis of secondary standards to transform data among reference scales and estimate the uncertainty inherent in these transformations. We apply the algorithm to a compilation of known-origin keratin data published over the past ~20 years. We show that transformation improves the comparability of data from different laboratories, and that the transformed data suggest ecophysiologically meaningful differences in keratin–water relationships among different animal groups and taxa. The compiled data and algorithms are freely available in the ASSIGNR r-package to support geographical provenance research, and more generally offer a methodology overcoming several challenges in geochemical data integration and reuse
Valutazione dell'impatto di linee-guida per la razionalizzazione della prescrizione degli esami preoperatori a pazienti ASA 1 e 2 sottoposti a chirurgia elettiva
No full textDottorato di ricerca in statistica medica e metodologia epidemiologica. 11. ciclo. A.a. 1998-1999. Coordinatore Enzo Ballatori. Tutore Maria Contina MarinucciConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
A Theorem on Homeomorphic Convergence and Some Applications
No full textBorsuk [ 3 ] has given interesting conditions under which a certain function space is separable (see Theorem 3. 1 ). We give a proof for Borsuk\u27s Theorem here and we show how it can be used to establish a useful theorem on homeomorphic convergence. We illustrate the utility of the theorem on homeomorphic convergence by stating and proving several of its consequences.
For example we show that the plane (E2) does not contain uncountably many pairwise disjoint contina each of which contains a simple triod (Corollary 4. 1 ). We prove that in an uncountable collection G of pairwise disjoint simple closed curves in E2 almost all elements of G must be converged to homeomorphically from both sides by sequences of elements of G (see Theorem 4. 3 ). The same technique allows us to prove the nonexistence of uncountably many pairwise dis -joint wild 2 -spheres in E3.
Another interesting consequence of Borsuk\u27s Theorem is Theorem 3. 4 which shows that in each set G consisting of uncountably many compact subsets of a metric space, some element of G is an element of convergence. Proofs for this theorem do not often appear in the literature, and, as far as the author knows, the proof given here does not appear in the literature.
We wish to emphasize that all the proofs given in this report were constructed by the author without reference to the literature, in fact the author was unaware of the references until after the proofs were given. We given reference at the end of the paper where proofs in the literature can be compared with the proofs given here.
We wish to emphasize that all the proofs given in this report were constructed by the author without reference to the literature, in fact the author was unaware of the references until after the proofs were given. We given reference at the end of the paper where proofs in the literature can be compared with the proofs given here
CONSERVATION, ECOLOGY, AND EVOLUTION OF MIGRATORY BEHAVIOR IN THE PAINTED BUNTING (Passerina ciris)
No full textIn animal migration studies, determining the migratory connectivity of different species is a crucial step to understand the ecology and evolution of complex behavioral traits as well as to implement effective conservation management plans of declining species. Intrinsic markers, such as stable isotopes and genetic markers, in conjunction with miniaturized light-level geolocator devices, provide high resolution tools to study the ecology and evolution of migration in birds smaller than 20 grams and offer insight on the breeding population of origin of those individuals trapped and sold in the international pet trade market. For example, from 2005 to 2009, CITES documented more than 317,000 live birds sold annually within an industry estimated to be worth billions of US dollars per year. In this context, migratory species can be particularly difficult to protect because any management effort would necessarily involve cooperation among different countries with distinct laws and regulations. A case in point is the Painted Bunting (Passerina ciris), which breeds primarily in the United States and winters in Mexico, Central America, southern Florida, and the Caribbean. I provide a new library of polymorphic microsatellite loci and offer a new tool for genetic population structure studies, forensic analyses, and conservation management of the Painted Bunting and other related species of the genus Passerina. My results suggest that buntings harvested in Central America for the retail market belong to the western breeding population as opposed to the smaller Atlantic breeding population. However, a percentage of both populations come into contact at the wintering grounds in the Yucatan Peninsula where conservation efforts might need to be strengthened.Furthermore, during my investigations on the molting ecology of the Painted Buntings, I found that birds breeding in Oklahoma and molting in Sinaloa, Mexico, show a clear bimodal pattern of stable isotope ratios in their flight feathers, as previously demonstrated in this species, suggesting that some birds may initiate molt immediately upon arrival in northwestern Mexico whereas others may delay molt. I used geologger tags to test whether differences in the timing and route of fall migration movements were related to stable isotope signatures in primary feathers. I observed variation among individuals in migration routes, wherein birds from the same breeding population differed greatly in their use of molting and wintering locations. However, I did not find a relationship between isotope signatures and the timing or route of fall migration.Furthermore, I investigated possible relationships between variation in two candidate genes implicated in the control of migratory behavior (CLOCK and ADCYAP1) and several aspects of fall migration including initiation date, arrival at molt/stopover sites, and duration of the first leg of fall migration. I evaluated the mutation rate of these candidate genes through an Approximate Bayesian Computation (ABC) coalescent approach and studied the effect of natural selection on their allele frequencies across populations. I found that millennial scale summer temperatures and longitude likely affected the current genotypes of CLOCK and ADCYAP1 in three sampling populations. To search for novel genes associated with migratory performance, I implemented 454 next generation sequencing and generated over 48,000 DNA sequences distributed over the Painted Bunting genome. I assembled an extensive library of candidate genes by annotations extracted from the Mouse Genome Informatics database and I focused on the following candidate genes: ADRA1d, ANKRD17, CISH, and MYH7. I tested these genes across avian migratory and non-migratory species, revealing a surprising degree of allelic variation in some genes. MYH7 correlated with speed of migration (km/day) and body mass across 11 species of songbirds in addition to two novel uncharacterized polymorphic genes that strongly correlated with duration of migration in the Painted Buntings
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